This invention relates to a steering mechanism for an automobile and more particularly, to an improved steering mechanism for an automobile which is adapted to eliminate excessive play when the automobile is running straight and reduce required steering force when high load is applied to the steering mechanism.
There have been known a variety of prior art steering mechanisms for automobiles and one of the prior art steering mechanisms is shown in FIG. 5 of the accompanying drawings. The prior art steering mechanism generally comprises a housing 1 in which a column shaft 2 is rotatably mounted by means of bearings 3, 3'. A pinion 4 is mounted on the column shaft 2 and a rack bar 5 engages the pinion 4 substantially at right angles to the pinion. The housing 1 defines an opening 6 behind the rack bar 5 and a support yoke 7 is received in the opening 6 for axially slidable movement therein. The support yoke 7 has a roller 8 rotatably mounted within the yoke and a spring 10 is interposed between the support yoke 7 and a yoke stopper 9 fitted in the opening 6 at one or the outer end of the opening so as to normally bias the support yoke 7 towards the rack bar 5.
However, in the prior art steering mechanism having the components constructed and arranged as described hereinabove, the central area 5a of one side of the rack bar 5 is recessed so that the roller 8 will not abut against the rack bar 5, but can abut against the opposite ends 5b of the recessed central area 5a as shown in FIG. 6. Furthermore, in the prior art steering mechanism, the inner end of the support yoke 7 abuts against the central area 5a of the rack bar 5, but does not abut against the opposite ends 5b of the central area.
Therefore, the prior art steering mechanism has the drawback that under high load conditions, the efficiency is low at the central area of the rack bar and when the steering wheel is rotated, the inner end of the support yoke 7 abuts against the central area of the rack bar whereas the roller 8 abuts against the opposite ends of the rack bar central area whereby the abutment relationship with respect to the rack bar transfers between the support yoke and roller and thus, the transfer is not smooth. Furthermore, the prior art steering mechanism has the drawback that in, order to make the rack bar rigid, if the spring 10 applies an increased load thereto, the support yoke contacts the rack bar with an excessively high friction.